A case study of a severe hailstorm in Mendoza, Argentina, during the RELAMPAGO-CACTI field campaign

BECHIS, HERNAN; ALVAREZ IMAZ, MILAGROS; SIMONE, INES; GALLIGANI, VICTORIA; CANCELADA, MAITE; PISCITELLI, FRANCO; MALDONADO, PAULA; SALIO, PAOLA

Workshop; 3rd European Hail Workshop; 2021

Karlsruhe Institute of Technology

Storms in the Mendoza province, Argentina are known for frequently producing large and severehail. The environmental conditions and strong interaction with topography there provide uniqueconditions for the initiation and intensification of severe storms. The RELAMPAGO (Remote sensingof Electrification, Lightning, And Mesoscale/microscale Processes with Adaptive GroundObservations) and CACTI (Clouds, Aerosols, and Complex Terrain Interactions) field campaigns weredeployed between October 2018 to April 2019 over west-central Argentina, and have collectedunprecedented Intensive Observation Periods (IOPs) in the region. During the IOP number 10 onNovember 26, 2018, a severe hailstorm developed and moved across the observational network inthe Mendoza domain. 4-cm diameter hail was reported over multiple hailpad sites and with in-situmeasurements. Several soundings, mobile and fixed radar observations, and surface observationsare available for this case, along with 1-min GOES-16 ABI Mesoscale Domain Sector (MDS) datacoverage.High-temporal frequency soundings and surface observations collected prior to the convectioninitiation are analyzed, allowing a detailed description of the storm environment. Processes leadingto convective initiation over the higher terrain include the development of the upslope flowassociated with a mountain-plains circulation, the weakening and ascent of the nocturnal inversionowing to diurnal heating and mixed-layer growth, and upper-level cooling related to the advance ofa shortwave trough. Once the storm initiates, it moves eastward towards the lower terrain, wherethe higher CAPE and deep-layer shear environment support the transition into a supercell. It is afterthis transition that the most severe hail at the surface is observed.